I've heard them claim it sunk back beneath the surface of the Earth. They'll claim that because the bible says that's where some of the water came from in the first place. "Great well springs from the depths", or somethng like that. They think there's just a mass of water mixing in with the magma I guess.

I've heard others claim it simply evaporated away into space, and is lost from the panet forever.

Of course, there is not scientific evidence of this, nor is there anyways this could scientifically be true, but they don't bother with the particulars, or specifics... as long as they already have an answer.

Further to this question,
If the atmosphere is (and was) set up in such a way in order to sustain life, how did the people and animals on the ark survive. At 15 cubits higher than all mountains for 150 days there would be insufficient oxygen and super cold temps.

Even if the ATM rose as is with the water, that 5.5 mile shift would have thrown so much off to be lethal to most air breathing life. That is like believing you can tunnel to the center of the earth and survive (like the movies) - not enough faith in the universe to make either story factual.

“Truth does not demand belief. Scientists do not join hands every Sunday, singing, yes, gravity is real! I will have faith! I will be strong! I believe in my heart that what goes up, up, up, must come down, down, down. Amen! If they did, we would think they were pretty insecure about it.”
— Dan Barker —

Besides this answer is easy. God can do anything, including break the law of conservation of energy/matter. Bringing the water into creation and taking it out is nothing for a god such as Yahweh. There is no reason that a YECist would assume that the earth operates as a closed system.

Besides this answer is easy. God can do anything, including break the law of conservation of energy/matter. bringing the water into creation and taking it out is nothing for a god such as Yahweh. There is no reason that a YECist would assume that the earth operates as a closed system.

Yeah, but I like YECers better. Especially if you pronounce it phonetically.